The Ligand Assay and Analysis Core will serve virtually all eligible projects identified in this U54 Center application. In brief, the Core will: (1) prepare and purify labeled ligands for assays, agonist/antagonist binding studies, or immunocytochemistry; (2) provide estimates of the concentration of hormones or other regulatory molecules by RIA, chemiluminescent, immunometric, and bioassay procedures; (3) transfer relevant ligand preparation and assay technology procedures to projects; and (4) develop (10% effort) new or improved procedures required by the evolving investigative needs of funded projects eligible for Core access. The primary drive for establishing this Core laboratory is to provide high-quality technical services to U54 Center-related projects that require assay reagents, labeled ligands, and estimates of hormone concentrations. This services will benefit multiple U54 and Reproductive Sciences projects, since no mechanisms are available otherwise to obtain high-volume assays and/or high purified ligands required for investigations with isolated cells or particulate fractions of reproductive cells or tissue. Projects requiring new ligands or assays cannot justify the time or effort of a technician to establish, validate, and perform these procedures. A central facility will allow the U54 Center to meet the needs of all projects, enhance their productivity, implement a uniform set rationale for proposing this Core is to provide an efficient mechanism whereby new or improved (including non-radioactive) methods can be implemented for estimating amounts of peptides, growth factors, and steroids in multiple cell-culture and body fluids. This Ligand Assay and Analysis Core will thus serve the immediate and future needs of eligible reproductive-science projects in this U54 Center that require a dedicated ligand and assay central facility to conduct, develop, validate, and implement relevant measurement and analysis techniques.